Radiation detection element, radiation detection apparatus, x-ray ct apparatus, and manufacturing method of radiation detection element

Abstract

A radiation detection element according to the present invention includes: a single-crystal semiconductor substrate configured to convert incident radiation into an electric charge; a first cathode electrode provided on a first main surface of the single-crystal semiconductor substrate, the first cathode electrode having a first thickness; a second cathode electrode provided so as to face a side surface of the single-crystal semiconductor substrate, the second cathode electrode having a second thickness that is smaller than the first thickness; and an anode electrode provided on a second main surface of the single-crystal semiconductor substrate, the second main surface being on an opposite side of the first main surface.

What is claimed is: 
     
         1 . A radiation detection element comprising:
 a single-crystal semiconductor substrate configured to convert incident radiation into an electric charge;   a first cathode electrode provided on a first main surface of the single-crystal semiconductor substrate, the first cathode electrode having a first thickness;   a second cathode electrode provided so as to face a side surface of the single-crystal semiconductor substrate, the second cathode electrode having a second thickness that is smaller than the first thickness; and   an anode electrode provided on a second main surface of the single-crystal semiconductor substrate, the second main surface being on an opposite side of the first main surface.   
     
     
         2 . The radiation detection element according to  claim 1 , wherein the first cathode electrode and the second cathode electrode are integrated. 
     
     
         3 . The radiation detection element according to  claim 1 , further comprising an insulating layer provided between the side surface of the single-crystal semiconductor substrate and the second cathode electrode. 
     
     
         4 . The radiation detection element according to  claim 3 , wherein the second cathode electrode and the insulating layer have respective thicknesses that are determined such that a sum of the thickness of the second cathode electrode and the thickness of the insulating layer is a predetermined value and that the insulating layer is thicker than the second cathode electrode. 
     
     
         5 . The radiation detection element according to  claim 1 , wherein the single-crystal semiconductor substrate includes cadmium telluride. 
     
     
         6 . The radiation detection element according to  claim 1 , wherein the single-crystal semiconductor substrate includes cadmium zinc telluride. 
     
     
         7 . The radiation detection element according to  claim 1 , wherein the single-crystal semiconductor substrate includes any of cadmium tungstate, sodium iodide, and cesium iodide. 
     
     
         8 . A radiation detection apparatus comprising the radiation detection element according to  claim 1 , the radiation detection element being provided in plurality and arranged in a planar manner. 
     
     
         9 . The radiation detection apparatus according to  claim 8 , wherein the plurality of radiation detection elements are arranged without intervals in a first direction and in a second direction perpendicular to the first direction. 
     
     
         10 . The radiation detection apparatus according to  claim 8 , wherein the plurality of radiation detection elements are arranged without intervals in a first direction and at intervals in a second direction perpendicular to the first direction. 
     
     
         11 . A radiation detection apparatus comprising:
 a plurality of radiation detection elements that include the radiation detection element according to  claim 1  and a radiation detection element not having the second cathode electrode, the plurality of radiation detection elements being arranged without intervals in a first direction and in a second direction perpendicular to the first direction,   wherein, among the plurality of radiation detection elements, the radiation detection element according to  claim 1  is arranged as an outermost radiation detection element, and   the radiation detection element according to  claim 1  does not have the second cathode electrode on a side surface adjacent to another radiation detection element among side surfaces of the single-crystal semiconductor substrate and has the second cathode electrode on a side surface not adjacent to another radiation detection element among the side surfaces of the single-crystal semiconductor substrate.   
     
     
         12 . The radiation detection apparatus according to  claim 10 , wherein
 the single-crystal semiconductor substrate has two first side surfaces perpendicular to the first direction and two second side surfaces perpendicular to the second direction, and   the radiation detection element according to  claim 1  has no cathode electrodes facing the first side surfaces and has the second cathode electrodes facing the second side surfaces.   
     
     
         13 . A manufacturing method of a radiation detection element, the manufacturing method comprising:
 a step of forming a first cathode electrode on a first main surface of a single-crystal semiconductor substrate that converts incident radiation into an electric charge, the first cathode electrode having a first thickness;   a step of forming a second cathode electrode so as to face a side surface of the single-crystal semiconductor substrate, the second cathode electrode having a second thickness that is smaller than the first thickness; and   a step of forming an anode electrode on a second main surface of the single-crystal semiconductor substrate, the second main surface being on an opposite side of the first main surface.   
     
     
         14 . The manufacturing method of the radiation detection element according to  claim 13 , wherein the single-crystal semiconductor substrate includes cadmium telluride. 
     
     
         15 . The manufacturing method of the radiation detection element according to  claim 13 , wherein the single-crystal semiconductor substrate includes cadmium zinc telluride. 
     
     
         16 . The manufacturing method of the radiation detection element according to  claim 13 , wherein the single-crystal semiconductor substrate includes any of cadmium tungstate, sodium iodide, and cesium iodide. 
     
     
         17 . An X-ray computed tomography apparatus comprising:
 an X-ray generation unit;   the radiation detection apparatus according to  claim 8  configured to detect X-rays emitted from the X-ray generation unit; and   a signal processing unit configured to process a signal output from the radiation detection apparatus.